LAS VEGAS (AP) Andre Ward vowed he would leave no doubt this time around. He didn't, turning the tables on a big puncher and stopping Sergey Kovalev in the eighth round Saturday night to win their light heavyweight title rematch.

The undefeated Ward turned the fight around with a big right hand that wobbled Kovalev, then swarmed all over him. Kovalev was in the neutral corner and Ward was landing shots to the body when the Russian sat on the ring rope and referee Tony Weeks signaled an end to the bout at 2:29 of the eighth.

"I knew this time it was going to be different," Ward said.

In a lot of ways it was the same, until Ward - who was knocked down in the first fight - showed he was a big puncher, too, with a right hand that made Kovalev's right leg wobble and signaled the beginning of the end to the bout.

The fight had been close, with Kovalev (30-2-1) winning the early rounds before Ward (32-0) began making adjustments and Kovalev began tiring. Both fighters complained of dirty tactics and Weeks spent a lot of his time breaking up clinches.

Ward won the first fight in November, coming back from a second round knockdown to get a controversial decision. The rematch seemed just as close until Ward landed the right hand that caused Kovalev's legs to wobble.

"He's a great fighter," Ward said. "You've got to raise your game to the next level and thankfully that's what we did tonight."

Kovalev complained that Ward hit him with two low blows in the final exchange, forcing him to sit on the first rope.

"Why stop the fight?" he said. "I could have continued to fight."

The fight was rough and tumble from the beginning, much like when the two met the first time when both were unbeaten. But while Kovalev was supposed to be the puncher it was a big right hand by Ward that landed midway through the eighth.

"I could tell he was reacting to my body shots and I knew I had him then," Ward said. "I knew he was hurt."

Ward was up by a point on two scorecards and down three points on the third going into the eighth. But Kovalev was fading, just as he had in the first fight, and he picked up the pace. Kovalev was credited with throwing 407 punches to 238 for Ward, and out landing him 95-80.

The AP had Kovalev ahead by a point going into the final round.

"I don't know, I can't explain it," Kovalev said. "I thought I was doing very good. I was better and he was better this fight. I didn't feel like I was getting knocked down by the power of his punches."

Ward, who won an Olympic gold in 2004 and hasn't lost a fight since he was 12, took a few rounds to find his mark but once he did the two engaged in close rounds that were difficult to score. The crowd at Mandalay Bay thought otherwise, roaring at every punch landed by Ward and chanting his nickname.

There was genuine dislike between the two fighters, born largely out of their first fight. Neither made any effort to touch gloves when given their final instructions, and once the bell rang, they both went after each other.

The fight itself played out early somewhat like the first one, with Kovalev starting out aggressively and Ward trying to find his rhythm. Weeks, meanwhile, was working hard to keep control as the two fighters clinched and hit each other behind the head, with Ward landing a low blow in the second round that doubled Kovalev over and caused Weeks to pause the bout.

Ward vowed before the fight to leave no doubt this time, after escaping with a win that many at ringside questioned in the first fight. He appeared confident he would do just that, coming into the ring doing a little dance before turning to salute the crowd.

Kovalev, a Russian who lives in Los Angeles, had complained bitterly about the scoring in the first fight, though he appeared to run out of gas as the fight went on.

Ward was paid $6.5 million for the rematch, while Kovalev got a percentage of the gate and the pay-per-view.

In another fight, two-time Olympic gold medalist Guillermo Rigondeaux retained his super batamweight title on a first-round knockout over Moises Flores when he landed a punch after the bell.

Rigondeaux and Flores were trading punches when the bell rang to end the first round and both threw after the bell. Rigondeaux's punch landed, and Flores dropped to the canvas where he was counted out.

Nevada boxing officials huddled for several minutes and watched the replay before ruling the punch was legal.

Rigondeaux, who won his gold medals for his native Cuba, improved to 18-0 with 12 knockouts as a pro, while Flores, from Mexico, fell to 25-1.